The present invention broadly relates to a new and improved apparatus for collating folded printed products, especially signatures or sheets.
In its more particular aspects, the present invention concerns a new and improved apparatus for collating folded printed signatures or sheets in which the printed signatures or sheets are deposited in each case in a straddling position or posture by a number of infeed devices or feeding conveyors upon collating conveyors provided with pusher or pushing entrainment members. There are provided a plurality of such collating conveyors which extend substantially parallel to one another at a substantially uniform or equidistant circumferential spacing from one another about an axis of revolution or rotation. These collating conveyors revolve or rotate about such axis of revolution or rotation.
Such type of collating apparatus is disclosed in the German Published Pat. No. 3,620,945.7, or the extensively cognate British Published Patent Application No. 2,177,380, and the aforementioned corresponding U.S. Pat. No. 4,684,116, granted Aug. 4, 1987. In contrast to other prior art collating apparatuses, for instance as disclosed in Swiss Patent No. 535,696, granted Apr. 15, 1973, and Swiss Patent No. 650,729, granted Aug. 15, 1985, which possess only a single, as a general rule linear collating conveyor, the initially referred to collating conveyor as disclosed in the aforementioned U.S. Pat. No. 4,684,116, is capable of collating appreciably more printed signatures or sheets per unit of time. This is attributable to the fact that each of the collating conveyors, during its movement between two neighboring infeed devices, accomplishes one revolution about the axis of revolution or rotation and the entrainment members of such collating conveyors, during such revolving motion, are advanced or forwardly displaced by an amount corresponding to the spacing from the next downstream located infeed device. Viewed in space the entrainment members thus describe a helical or spiral-shaped path of travel. Therefore, the infeed devices can deliver the folded printed signatures or sheets practically in the same number per unit of time as such are outputted, for instance, by an upstream arranged printing press. The entrainment members thus can be advanced relatively slowly, in other words, without there existing the danger of damaging the printed signatures or sheets.
What is important to take cognizance of with respect to the heretofore known collating apparatus is that the infeed devices deposit the printed signatures or sheets upon the collating conveyors moving therepast such that they always come to lie forwardly or downstream of one of the arriving pusher entrainment members. This is only possible if the infeed devices and the collating conveyors are controlled and synchronized or coordinated with respect to one another such that the printed signatures or sheets come to lie at a spacing, even if the same is small, forwardly of the just arriving entrainment member of the relevant collating conveyor. In other words, a certain distance or spacing prevails between the arriving entrainment member and the trailing edge of the printed signature or sheet as viewed in the direction of conveyance of the collating conveyor.
As far as the initially deposited printed signature or sheet is concerned this is of no great significance. This is so because the point or location of deposition upon the collating conveyor does not move since this first deposited printed signature or sheet, following its placement upon the associated collating conveyor, so-to-speak remains "stationary", that is to say, does not move relative to the collating conveyor upon which it is deposited, until it is again so-to-speak "passed" or "caught up with" by the associated pusher entrainment member and only then will such previously deposited printed signature or sheet be forwardly displaced or advanced. However, as far as each further printed signature or sheet is concerned, which comes to bear upon a previously deposited printed signature or sheet, this aforedescribed spacing is of significance. This is so because each of such further deposited printed signatures or sheets, by virtue of the friction prevailing between such further deposited printed sheet and the printed sheet disposed therebelow, can be forwardly advanced or displaced from the moment that it is laid upon the previously deposited printed signature or sheet without such further or subsequent deposited printed signature or sheet directly contacting or bearing at the pusher entrainment member. The result of this type of operation is that the edges of the printed signatures or sheets collated by the collating conveyors are not congruently aligned or squared up with respect to one another. As a result, there exists the necessity of aligning or squaring up the groups of printed signatures or sheets which have been collated at the collating conveyors of the heretofore known apparatus prior to performing the next intended operation, for instance, prior to stapling or stitching or otherwise binding together the collated printed signature or sheets.